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A stunning centerpiece for any meal, my Roasted Boneless Leg of Lamb is a recipe you can count on. With just 15 minutes of prep and a handful of everyday ingredients, my no-fail method relies on one simple technique: seasoning both the inside and the outside of the roast. And that means a succulent, deeply flavorful roast every single time.
Cooking a leg of lamb may seem daunting, but it’s easier and faster than you might think. You can make a tender, juicy roast with just 15 minutes of prep and less than 2 hours of roasting time. This dish is perfect for Easter, spring holidays, celebratory family meals, or dinner parties year-round.
This extra step might seem unnecessary, but I promise you, it’s worth it. It’s the secret to a mouthwatering meal with minimal effort. Using boneless lamb makes this possible; plus, it cooks faster, is easier to carve, and fits well in a roasting pan.
“I made this last night and it’s become an instant family favourite … when my fussiest eater says “you can make that again, Mum”, you know it’s a winner! I teamed it with a side salad (it was a 40 degree day here in Australia) and a red wine reduction which teamed beautifully.”
helen
Table of Contents
Why This Recipe Works
- Seasoning the Roast Both Inside and Out. Most recipes have you rub the outside of the netted roast. Here you’ll take a few extra minutes to untie and unroll it, to rub the garlic-Dijon-herb paste deep into the meat. This seasons the whole roast, not just the crust.
- High-Heat Sets the Crust. Starting the lamb at 425°F creates a gorgeous, herbaceous crust. Once the crust is set, you’ll drop the heat to 350°F so the inside cooks gently and evenly.
- More than a Rub. The combination of Dijon mustard, garlic, and Herbes de Provence isn’t a typical rub; it’s a flavor infusion and helps keep the meat moist all the way through.
- Easy Carving. By using a boneless roast and tying it, you end up with a uniform, even shape. It cooks more evenly and makes carving at the table simpler. No awkward bone to cut around.
Roasted Boneless Leg of Lamb Ingredients
- Boneless Leg of Lamb: Look for a 5-6 pound roast. It will likely come rolled in netting that you’ll remove to season the inside.
- Dijon Mustard: Choose a quality brand that’s you’d happily slather on a sandwich.
- Garlic: Use fresh, plump, firm garlic cloves.
- Herbes de Provence: A mix of dried herbs that varies, usually: rosemary, thyme, oregano, marjoram and sometimes lavender.
- Olive Oil: Use a good quality extra-virgin olive oil.
- Kosher Salt: I use Diamond Crystal brand. If you use Morton, please be aware it’s almost twice as salty, so you’ll need to halve the amount.
- Freshly Ground Black Pepper
How to Make Roasted Boneless Leg of Lamb
Prep Lamb; Make Herb Paste to Rub Inside and Out: If the roast is wrapped in netting, snip and remove it; then unroll. Trim hard or excess fat, leaving a thin layer on the outside. Mix the Dijon herb paste ingredients together in a bowl until emulsified. Spread some of the herb paste on the inside of the lamb, then roll and tie roast with kitchen twine. Rub the remaining paste all over the outside.Begin by preparing the roasting pan with a rack.
Roast in Two Stages: Let the lamb sit at room temperature while preheating the oven to 425°F. Roast for 15 minutes, then reduce heat to 350°F and continue cooking until the internal temperature reaches 135°F for medium-rare. (This typically takes 1 to 1 1/2 hours.)
Rest, Snip, and Slice: After roasting, let the lamb rest for 15-30 minutes before removing the twine and slicing. Remember, the temperature will rise slightly during resting. Slice roast and arrange on a platter to serve.
My Pro Tips for a Perfect Roast
- The Secret to a Perfect Medium-Rare: Use an instant-read thermometer to avoid the disappointment of overcooking. Pull the roast from the oven at 135°F, maximum.
- Trust in Carryover Cooking: Once you remove the roast from the oven, the internal temperature will continue to rise by 5-10 degrees. Your 135°F roast will become a perfect 140-145°F (medium-rare) as it rests.
- Don’t Skip the Rest: Letting the lamb rest for 15-30 minutes allows the juices to redistribute throughout the meat. If you slice it immediately, the juices will flow out onto your cutting board instead of staying in the roast.
- How to Tie the Roast: Don’t be intimidated by the kitchen twine. You don’t need a fancy butcher’s knot. Just roll the lamb back up into its original shape and tie it snugly in three places: one in the center and one at each end.
Simple Variations
- For Brighter Flavor: Add 1 teaspoon of fresh lemon zest to the herb paste.
- For a Rosemary-Forward Roast: Herbes de Provence already has rosemary, but if you’re a big fan (like I am), swap half of it for 1 tablespoon of finely minced fresh rosemary.
Your Questions, Answered (FAQ)
Yes. For this recipe, you must remove the netting. Removing it allows you to unroll the lamb and spread that incredible Dijon-herb paste inside the roast, which is the key to making every bite flavorful. Then you’ll re-tie it with kitchen twine.
I use a two-stage method: a 15-minute blast at 425°F to build a crust, followed by a long, steady roast at 350°F to cook it gently and evenly.
Your thermometer should read 135°F when you pull it from the oven. It will rise to a perfect 140-145°F (medium-rare) as it rests.
No. Do not cover it. Covering it with foil would steam the meat and prevent that delicious, crispy herb crust from forming.
My Key Temperatures for Lamb
Use this as your guide. Always pull the meat from the oven 5-10 degrees before your target temperature.
- 130-135°F (Pull Temp): Medium-Rare (My #1 recommendation)
- 140-145°F (Pull Temp): Medium
- 150°F+ (Pull Temp): Medium-Well (I advise against this, as the lamb will be less tender.)
What to Serve Alongside
This roasted boneless leg of lamb is a delicious centerpiece for any special meal. The herb-infused meat pairs beautifully with a variety of side dishes.
- Gratin Dauphinois (Creamy classic French potato gratin.)
- Lyonnaise Potatoes (Another delicious French potato side dish with caramelized onions that’s made on your stovetop.)
- Fondant Potatoes (These meltingly tender potatoes start on the stovetop and can finish in the oven while your lamb roast rests.)
- Mashed Red Potatoes (Ultra creamy with a method that might surprise you.)
- Brioche Dinner Rolls (Tender, buttery and so easy to make with this no-knead recipe.)
- Sugar Snap Pea Salad (The perfect pair to roast lamb if you’re making it in the springtime.)
- Strawberry Spinach Salad (With pecans, goat cheese, and a tangy, honey sweetened balsamic vinaigrette.)
- Strawberry Spinach Walnut Salad (A riff on the salad above with walnuts and a Strawberry Vinaigrette.)
- Caesar Salad (Because you can never go wrong with this classic salad.)
Roasted Boneless Leg of Lamb
Video
Equipment
- Oven-Safe Baking Rack Ideal for perfectly roasted boneless leg of lamb!
Ingredients
- 5 1/2 pound boneless leg of lamb
For the Dijon Herb Paste
- 1/4 cup extra virgin olive oil
- 2 tablespoons Dijon mustard
- 4 medium garlic cloves minced
- 2 tablespoons dried Herbes de Provence (recipe note #1)
- 1 tablespoon kosher salt (recipe note #2)
- 1/2 teaspoon freshly ground black pepper
Instructions
- Prep Pan and Lamb: Place an oven-safe rack inside a rimmed baking sheet lined with foil (for easy cleanup). If lamb roast is tied, untie and unroll. Trim away thick areas of fat and tendon from the top and bottom of the roast, leaving a thin layer of fat on top.
- Make the Herb Paste: Whisk together all Dijon Herb Paste ingredients in a medium bowl until they emulsify into a uniform paste.
- Season Inside and Out: Spread 1/3 of herb paste all over underside of roast. Roll roast back up into its original shape and snugly tie in the center and at both ends with three lengths of kitchen twine. Rub outside all over with remaining herb paste. Transfer roast, seam side down, to rack on prepared baking sheet and let stand at room temperature while the oven preheats.
- Preheat Oven: Preheat oven to 425 °F (218 °C).
- Roast High: Roast lamb in hot oven for 15 minutes. Transfer roast to cutting board; let stand 15-30 minutes before slicing.
- Roast Low: Reduce heat to 350 °F °F (177 °C) and cook until an instant read thermometer inserted into the center registers 135˚F (for medium rare – the temperature will rise as the roast rests before slicing), 1 to 1 1/2 hours.
- Rest and Slice: Transfer the roast to a cutting board; let stand 15-30 minutes before slicing. Snip the twine with kitchen shears; remove and discard. Slice the roast thinly (about 1/4-inch) and arrange on a platter. Serve.
Notes
- Salt: I develop all my recipes with Diamond Crystal brand kosher salt. If you are using Morton’s, which is much saltier, I recommend cutting the salt in the paste to 2 teaspoons.
- My Favorite Tweaks: I personally love adding 1 teaspoon of fresh lemon zest to the paste for a bit of brightness. If you’re a big rosemary fan, feel free to use 1 tablespoon of Herbes de Provence and 1 tablespoon of minced fresh rosemary instead of the 2 tablespoons of dried.
- The Temperature is Key: Please, trust me on this—use an instant read thermometer! Pull the roast at 135°F for a perfect medium-rare. It will look underdone, but the temperature will rise to a perfect 140-145°F as it rests. This is the single most important step for a juicy, tender roast.
Nutrition
Nutrition information is automatically calculated, so should only be used as an approximation.
Delicious!!
I’m so glad you enjoyed this, Dianna!
Just enjoyed a small lamb roast (1.64 lbs) adjusted cook time and made the suggested Lyonnaise potatoes. Delicious!! Your paste recipe is very similar to what i came up with when i do a rack of lamb. additionally, We roll rack in panko and chopped nuts (walnuts or macadamia)…..but that wouldn’t work for this. Your recipe is a keeper! Thank you
Thank you, Bianca – for your kind words and your cooking notes! So glad you’re enjoying the recipe.
I made this roast tonight, doing everything Marissa recommended: trimming the fat and mixed all the ingredients to cover the meat with delicious flavour. It was so delicious! I’ve been making roast lamb for a number of years and this simple recipe was the best of all. Her suggestions about when to remove it from the oven meant the meat wasn’t over done, but tender and cooked just to the spot between rare and medium. Thank you so much!
You made my day, Riesah! I’m so glad you’re enjoying the recipe.
This was my first attempt at cooking boneless leg of lamb and it turned out great. I purchased my meat from Costco and it was 5.72lbs, followed your instruction and I am greatly pleased. My meat is juicy and cooked to medium on the end pieces and medium rare in the middle, just the way I like it.
That’s wonderful to hear, Sharon! Thank you for coming back to let me know.
I have only a 2-lb. lamb roast on hand. Q: Will it work if I simply halve the recipe and reduce the cooking time by half here, or would some other adjustments be recommended? Thank you kindly for your reply.
Hi K.K.! Once you cook for the initial 15 minutes at the higher temperature, the roast will need another 15 to 20 minutes per pound. That said, be sure to check with a meat thermometer (ideally instant read) and take the roast out of the oven when it registers 135˚F in the thickest part for medium-rare and let rest until it reaches the target temperature of 145˚F. I hope that helps!
Is it OK to prepare and let marinate overnight then cook the next day?
Hi Al! Yes, absolutely.
Very easy and turned out great!
After seeing the comment below “Just hope I don’t overcook it. Don’t have thermometer”, I just want to stress the importance of paying the price for a high quality oven thermometer (to measure oven temp – don’t trust the setting level on oven), a leave-in probe thermometer and an instant read thermometer. I find cooking guidelines (x minutes per pound) to be highly inaccurate as meats often increase in temp slowly and then do a rapid rise towards the end. The time window for the perfect temp you want is very narrow.
That’s wonderful to hear, Jeff! So true that every oven is a little bit different and good thermometers are indispensable kitchen tools.
OH MY GOODNESS!!! My husband and I had never had lamb. I made this and it was wonderful! Thank you for the very easy directions.
So brave to start off with a roast, Tess! I’m so happy that you and your husband enjoyed it so much. Thank you for coming back to let me know.
It was perfectly delicious!
So glad you enjoyed it, Luwayna!
After turning heat down to 350⁰, how many more minutes per pound should I leave in oven?
Hi Joyce! After the initial 15 minutes at the higher temperature, I find that the roast takes another 15 to 20 minutes per pound. That said, I recommend testing for doneness with a meat thermometer (pull the roast when it registers 135˚F in the thickest part for medium-rare and let rest until it reaches the target temperature of 145˚F).
Made this last Sunday for me and hubby; we’re big lamb lovers! I didn’t use any mustard but made ‘paste’ from herbs from my garden- parsley, rosemary, fresh garlic, and some Italian herb blend. I also didn’t retwine. It was amazing- perfectly med-med rare. Thank you for the recipe.
Hi Cathy! So glad that you and your husband enjoyed it and that you used herbs from your garden!
Just put in oven! Smells great can’t wait…. Just hope I don’t overcook it. Don’t have thermometer
I hope it turns out beautifully, Jessie!
Believe it or not, but I’ve never actually cooked a leg of lamb. As you noted, there is a bit of a mystique around lamb. However, this recipe looks straightforward and delicious! Perfect for a fancier spring meal!
Oh wow, David! You’ve got to give this a try – I think you’ll love it!
Marissa, that’s one beautifully roasted leg of lamb! I am a huge fan of lamb (well, I love red meat 🙂 ) and I love rare. The Dijon herb paste is perfect.
Thanks, Angie. We’re simpatico!
This looks just delicious Marissa! And so perfect for any major holiday, especially Easter! A total showstopper and so easy too!
Thanks so much, Mary Ann!